A Visionary Call to Action
Researcher Sonia Gavasso, PhD, with the Neuroimmunology Lab at Haukeland University Hospital in Bergen, Norway, recently chatted with Fluidigm about the role of mass cytometry in her team’s cancer research. Gavasso anticipates that mass cytometry, or cytometry by time-of-flight mass spectrometry (the technology used in the CyTOF® system), will help to align diagnostics with current biological understandings of cancer, noting that monitoring therapies is key to making better decisions.
Defining immunotherapy approaches
There’s always talk about the importance of developing personalized therapies in the clinic, but she believes there should also be personalized monitoring. Fueling her work at University of Bergen through self-described fascination and love of science, Gavasso explained, “I have a passion for biology and an imagination for complexity. When I moved to Norway and joined the Haukeland University Hospital, I began studying immunology and central nervous system diseases, which are highly complex. That’s where mass cytometry comes in.”
In the Expert Review of Molecular Diagnostics paper, “Single-cell proteomics: potential implications for cancer diagnostics,” Gavasso et al. issue an inspiring call for researchers to develop solutions addressing key problems in sustainable health care. “We believe new and emerging technologies will allow us to move from mostly empirical decisions to tailored treatments enabling fast and early decisions regarding response,” she said. “It would be the holy grail, even before treatment starts.”
In human medicine, it’s difficult to predict who will respond to an immunotherapy. The paper outlines an integral need for hands-on, simple technology to monitor response over time, rather than administering long-term treatment before differentiating between responders and nonresponders.
Mass cytometry has amazing potential. I don’t want to use the word ‘revolutionize’, but it’s close to it. This is the first time we can clearly monitor the whole immune system for a really broad view of what’s going on and what we should do. ”
– Sonia Gavasso, PhD, Neuroimmunology Lab, Haukeland University, Norway
Gavasso wanted to get a view of the immune system and how it behaves during therapy. “One out of three people die from cancer and it’s increasing, so something has to happen. There’s a real need for single-cell analysis technologies that revolutionize what we can do in research to translate into clinical diagnostics and monitoring. With CyTOF technology,” she continued, “we can go much deeper into whole system immunophenotyping to see where these medications actually work and where the antibody binds and has an effect. This is a completely new, holistic way to look at and monitor the immune system.”
When she heard about CyTOF technology in 2009, Gavasso remembered, some were skeptical, but she was thinking: “‘We should absolutely do this.’ I was fascinated and super excited about it.” She visited scientists in Paris who had a mass cytometer and recalled being amazed seeing it in action. “In Norway, they like established procedures and technologies so we had to wait a long time, but we didn’t give up.” Their Helios™ was a gift to the Haukeland University Hospital and University in Bergen funded through a Bergen Research Foundation grant.
“We now have a Helios system and it’s running really well. We have our own dedicated mass cytometry team here to take care of the system and run mass cytometry at the hospital where we collect lots of cells in clinical trials.” Gavasso holds great hopes for mass cytometry, citing around 20 major cryobanks collecting cell samples for mass cytometry applications in cancer, rheumatic, neurological and central nervous system diseases and advanced therapies like cryoimmunotherapy and stem cell transplantation. “We plan to get another Helios, and we look forward to being able to expand our mass cytometry capabilities with tissue imaging.”
Advantages over flow cytometry
The visualization in mass cytometry data is a major plus for Gavasso. “With mass cytometry, we’re finally getting a view of the elusive immune response in immune therapies. Disease systems are so complex. It’s super that we can look at a certain cell but not lose information about what other cell types are doing, or where they are within the immune system. That is absolutely unbelievable,” she said.
“Previously, this type of information was difficult to obtain in a single analysis with flow cytometry, and mass cytometry clearly expands our horizon,” she noted, “so we can monitor complexity.” Her team reported debulking in leukemia during kinase inhibitor treatment as early as seven days after starting. They also saw where a medicinal antibody binds and in which cell subtype. “It is unprecedented. We would not do this on the flow cytometer. There are too many tubes that are difficult to combine and need lots of controls.”
Gavasso gave the example of how medications come to the field after successful clinical trials, but how they actually work is often unknown, so researchers like her must rush to explain the mechanistic action. For her, mass cytometry is the technology to discover what immune-modulating compounds do in the immune system. “I am a believer,” she said. “Mass cytometry has amazing potential. I don’t want to use the word ‘revolutionize’, but it’s close to it. This is the first time we can clearly monitor the whole immune system for a really broad view of what’s going on and what we should do.”
Her lab in Bergen is currently running major Helios projects for which they’re collecting tissue and cell samples. For one study, they’re using Helios to monitor cryoimmunotherapy response in prostate cancer. Another involves developing stem cell transplant treatment approaches for MS and for leukemia using CyTOF technology to understand how the immune system reconstitutes after stem cell transplantation and immune ablation. The team is also studying graft versus host disease in cancer.
Mass cytometry is not just equal to the methods they’ve been using, it’s actually much, much better. ”
– Sonia Gavasso, PhD
Papers in the pipeline
Gavasso has a proof-of-principle chronic myeloid leukemia (CML) study of treatment with nilotinib (Tasigna®), a tyrosine kinase inhibitor, in press. “We’d see clear changes three hours after initiating therapy and debulking after one week in this ENEST1 clinical trial substudy.” The team has the opportunity to collect samples before therapy and again within hours of treatment because they work closely with treating physicians in their clinical trial units. “In treatment,” Gavasso explained, “those early tests provide valuable information, so we don’t have to wait a whole year before we can label them responders or nonresponders.”
Ultimately, Gavasso dreams of being able to analyze immune cells in the brain in nervous system diseases. “It’s difficult to collect samples from within the central nervous system. And if we do get them,” she said, “it would be really cool to have excellent technologies for analyzing samples at any level from RNA to DNA to proteomics.”
Gavasso has several applications for working collaboratively with bioinformaticians to analyze biological, programming, algorithmic and statistical data from Helios, independent of what’s published. Her group works closely with lab mathematicians on topology, studying spatial properties preserved through stretching, crumpling, bending and twisting of objects to verify methodological usability.
Cytobank is a boon, especially for studying the clinical dataset needed to integrate with information from the mass cytometer. “CyTOF technology is better than how we did things before in the clinic, when we had to always select cells and parameters. This is really exciting,” she added. “Mathematicians here in Bergen actually come to us now asking for datasets.”
A new perspective
Mass cytometry for higher-parameter analysis of precious samples offers a number of advantages. “Personally, I was excited to let go of the two-dimensional flow cytometry approach,” she said. “Mass cytometry is amazing, but some people find change difficult and are reluctant to go high-dimension, saying, ‘We’ve been doing things this way forever. It works, so why change now?’” Gavasso’s answer: “Mass cytometry is not just equal to the methods they’ve been using, it’s actually much, much better.”
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